Wisdom On Machine Espresso From A Five-Year-Old
How Does Machine Espresso Work?
Machine espresso employs precise pressure and mind-blowing filter technology to create the perfect cup of coffee. How does it work exactly?
Espresso is made by forcing hot water under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.
The Group Head
The group head is the portafilter that you insert when brewing espresso coffee Machines for sale; e-bookmarks.com,. It disperses water in the portafilter, and regulates the pressure during the extraction. There are several different types of group head, each with their unique advantages and drawbacks. Some are designed for temperature stability while others are specifically designed to handle pre-infusion. Some are designed to control the lever. There are some that include a mix of features, like the E61 that is the classic choice among many baristas for its ability to offer multiple perks in a single package.
As you can see in the above image the group head comes with several notches where you put your portafilter, then twist it by hand to secure it. There is also a gasket made from rubber which is located inside the notches and helps to create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for an exact location of the portafilter which is crucial for an efficient extraction.
Aside from allowing you to easily insert your portafilter, the group head is responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it is always at the correct temperature to extract. It is important to realize that even a small differences can make the distinction between a good and a excellent espresso.
The Pump
The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines that use a lever. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being shot through the ground coffee inside the group head.
Pumps tend to be cheaper than piston-driven machines, and they tend to last longer. However, both types of machines can get damaged through overuse and lack of cleaning. They also add mechanical complexity and can lead to an expensive price for even the simplest models.
Certain espresso machines can eliminate the pump entirely and utilize steam pressure to make espresso. The drawback is that the boiler that produces steam also increases the temperature of water until it reaches boiling which can cause excessive extraction. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.
A majority of espresso machines utilize an rotary or a vibration pump. A vibration model uses an oscillating disk to create pressure, while the rotating model pushes hot water through the ground at a rapid speed. Both types of machine are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the part that heats the water to the ideal temperature to extract. The resulting steam reaches the portafilter containing the ground commercial espresso machine coffee, and gets funnelled down into the cup. The steam is able to create enough pressure to push the grounds of coffee through. This creates a crema on the top espresso machines of the espresso. This is one of the main characteristics of a good espresso.
There are three different types of espresso machines, each with distinct pumps and the temperature of the brew. There are various ways that the brew can be controlled and the size of the cup that the maker can create.
The first espresso machine with grinder machines were steam-types. They had only one boiler to make both brew and steam, however, the pressure they could generate was low - only two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso machine with frother machine is a semiautomatic that has an electric pump. These are what people imagine when they imagine an espresso coffee machine with milk frother machine. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is a great solution that combines human control with mechanised consistency.
The Filter
Espresso machines usually have a filter that separates the grounds of the coffee from hot water. The filter is also an important element of the temperature control system, as it keeps the machine from overheating.
A filter also helps with flavor, as it permits a longer flowering phase. This allows the beans to release their nuances, and improves extraction.
It is important to remember that even the best filter can make a bad cup of coffee. The quality of the beans and the extraction process, remain vital.
This is where the magic happens, and it's what makes an espresso really taste good. The grouphead, also called the brew head, is the place where the portafilter (the thingy you put the ground coffee in) sits when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight container to produce steam. The steam then moves hot water through the coffee grounds under high pressure. These kinds of machines are usually less expensive and easier to maintain than pump-driven models. They are however limited to create the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water through the grounds, and are far more portable than electric steam-driven machines.
